topic 8 Flashcards
Anabolic
Builds complex molecules, Are endergonic, biosynthetic, Ex.Photosynthesis
Catabolic reaction
Break down complex molecules, Are exergonic, degradative, Ex. Cellular Respiration.
The type of reaction that breaks down complex organic molecules with the release of energy is called catabolism
Exergonic
Reactions that occur when the products of a chemical reaction have less energy than the reaction’s reactants or substrates. They tend to occur in degradative reactions- complex molecules broken into simpler materials.
Endergonic
Reactions that occur when the products of a chemical reaction have more energy than the reactants or substrates of the reaction. They occur in biosynthetic reactions- complex molecules are produced.
Redox reactions
oxidation & reduction
Oxidation
Loss of electrons, Gain of Oxygen, loss of hydrogen, Results in many C-O bonds and a compound with a lower potential energy
Reduction
Gain of electrons, Loss of oxygen, Gain of hydrogen, results in many C-H bonds, results in a compound with a higher potential energy
Enzyme
substrate specifically is made possible by enzyme structures. Enzymes are very complex protein molecules with high molecular weights. The higher levels of protein structure allows for enzymes to form unique areas, such as the active site.
The induced fit model
The conformational changes and induced fit are the result of changes in the R-groups (globular- tertiary level of organization) of the amino acids at the active site of the enzyme, as the enzyme interacts with the substrate or substrates.
Mechanism of Enzyme Action
The surface of the substrate contacts the active site of the enzyme.
The enzyme changes shape to accommodate the substrate.
A temporary complex called the enzyme-substrate complex forms.
The activation energy is lowered and the substrate is altered by the rearrangement of the existing atoms.
The transformed substrate, the product, is released from the active site.
The unchanged enzyme is then free to combine with other substrate molecules.
Competitive Inhibition
In competitive inhibition, a molecule called a competitive inhibitor competes directly with the usual substrate of the active site of an enzyme. The result is that the substrate will have fewer encounters with the active site and rate of chemical reaction will be decreased. The competitive inhibitor must have a structure similar to the substrate to function in this way.
Competitive Inhibition may be reversible or irreversible. Reversible competitive inhibition may be overcome by increasing the substrate concentration- there are more substrate molecules to bind with the active sites as they become available and chemical reaction may occur more rapidly
Noncompetitive Inhibition
Involves an inhibitor that does not compete for the enzyme’s active site. In this case, the inhibitor interacts with another site on the enzyme.
It is also referred to as allosteric inhibition and the site the inhibitor binds to is called the allosteric site.
Feedback/End-product Inhibition
End-product inhibition prevents the cell from wasting chemical resources and energy by making more of a substance than it needs. Many metabolic reactions occur in an assembly-line type of process so a specific end product can be achieved.
Each step of the assembly line is catalyzed by a specific enzyme. When the end product is present in a sufficient quantity, the assembly line is shut down- this is usually done by inhibiting the action of the enzyme in the first step of the pathway.
As the existing end product is used by the cell, the first enzyme is reactivated. The enzyme that is inhibited and reactivated is an allosteric enzyme. When present in higher concentrations, the end product binds with the allosteric site of the first enzyme- bringing about inhibition.
Lower concentrations of the end product result in fewer bindings with the allosteric site of the first enzyme, and therefore, activation of the enzyme.
Anaerobic Respiration
If no oxygen is available, the pyruvate enters into anaerobic respiration. This occurs in the cytoplasm and it does not result in ATP. The products of anaerobic respiration are lactate or ethanol and carbon dioxide.
Aerobic Respiration
If oxygen is available, the pyruvate enters aerobic respiration in the mitochondria of the cell. This process results in the production of a large number of ATPs, carbon, and water.
Oxidation vs. Reduction reactions (redox) in CR
C6H12O6+6O2→ 6H2O+6CO2+energy
Glucose is oxidized because electrons are transferred from it to oxygen. The protons follow the electrons to produce water. The oxygen atoms that occur in the oxyzgen molecules on the reactant side of the equation are reduced. There is a large drop in the potential energy on the product side of the equation.
In the krebs cycle for cellular respiration
Any time there is a 5 to 4, carbon was removed in the krebs cycle
Anytime Co2 is released
Redox- NADH and FADH2 are produced. NAD+ and FAD+ picked up electrons
Phosphorylation
ADP becoming ATP
Glycolysis
Glycolysis is the process of sugar splitting. It uses no oxygen and occurs in the cytosol of the cell. No organelles are required. The sugar splitting proceeds efficiently in aerobic and anaerobic environments. Glycolysis occurs in both prokaryotic and eukaryotic cells.
Two ATPs are used to start the process.
A total of four ATPs are produced: a net gain of two ATPs.
Two molecules of NADH are produced.
The pathway involves substrate-level phosphorylation, lysis, oxidation, and ATP formation.
The pathway occurs in the cytoplasm of the cell.
The pathway is controlled by enzymes. Whenever ATP levels in the cell are high, feedback inhibition will block the first enzyme of the pathway, slowing down the process
Link Reaction
Once glycolysis has occurred and there is oxygen present, pyruvate enters the matrix of the mitochondria via active transport. Inside, pyruvate is decarboxylated, a reaction involving the loss of a carbon in the form of carbon dioxide to form the 2-carbon acetyl group. This is the link reaction. The removed carbon is released as carbon dioxide, a waste gas. The acetyl group is then oxidized with the formation of reduced NAD+. Finally, the acetyl group combines with coenzyme A (CoA) to form acetyl CoA.
The link reaction is controlled by a system of enzymes and produces acetyl CoA.
Krebs Cycle
a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate—derived from carbohydrates, fats, and proteins —into carbon dioxide. Acetyl CoA enters the Krebs cycle from the link reaction to continue the aerobic respiration. (0 ATP are used, 2 ATP are produced.)
ETC
Most of the ATPs from glucose catabolism are produced. This is the first stage of cellular respiration where oxygen is actually needed and occurs within the mitochondrial cristae. Embedded in the membranes, involved are molecules that are easily reduced and oxidized. These carriers of electrons (energy) are close together and pass the electrons from one another. One carrier protein is called coenzyme Q/ In this chain, electrons pass from one carrier to another because the receiving molecule has a higher electronegativity and therefore, a stronger attraction for electrons. In the process of ETC, small amounts of energy are released. The sources of the electrons that move down the electron transport chain are coenzymes NADH and FADH2. (O ATP are used, 32 are produced)
Glycolysis products and reactants
Glucose is the reactant, NADH, ATP, ad pyruvic acid are products
Oxidative Phosphorylation products and reactants
NADH and FADH2 are reactants, NADH, FADH2, oxygen, ADP, Pi phosphate are the products